Any downsides to oversizing radiators?

alheim

@Bob Bona‌ May I ask, why no hePEX? Small, flexible, w/ oxygen barrier, & possibly easier to connect to the rads.

Pipe the DHW direct ... hmm.

Bob Bona_4

The stuff expands alarmingly with higher temps. Potential for noise, chafing, hanging/routing hassles. PAP will give you everything plus near co efficient of copper expansion characteristics. Way better way to go. 1/2" Viega Fostapex or Uponor Multicor...Viega would be better for your limited use-read budget and tool availibility. Your runs and stub outs can be bent and stay straight. Hepex will want to curl.

No reason to pipe the DHW P/S.

alheim

You're right about the expansion:
1/2" Multicor Pex-Al-Pex: Linear Expansion Rate: 0.3" per 18°F rise per 100' (0.016" per degree F per 100').
1/2" hePEX: Linear Expansion Rate: 1.1" per 10°F rise per 100' (0.11" per degree F per 100') - almost 7x as much!

I could easily switch to Pex-Al-Pex using nothing but the appropriate compression fittings.

alheim

@Bob Bona‌ Is this what you're suggesting, piping the DHW direct:



Direct link to schematic.

^ Shades of @Eastman‌'s schematic.

How does this work with DHW Priority: when there is a call for DHW recovery, the radiator zone circulator stays off?

And when there is a call for heat to the rads, the DHW gets topped off (heat) regardless? What happens if you use an ODR at the boiler and the supply temp for the rads is lower than the required input at the DHW indirect - you'll end up sucking heat out of the DHW indirect. I guess you could set the boiler minimum water temp to avoid that, but it'll make the ODR semi-useless. Back to a 4-way w/ ODR!

Ironman

No, that's not it. Tee the supply and return lines right after they come out of the boiler to feed the indirect. Then set the boiler control to run only the domestic charging pump during a domestic call. The thermostatic bypass won't be in play when charging the indirect. The domestic pump goes in the supply line going to the indirect. All circ's will need check valves.

Bob Bona_4

Exactly. The DHW is a direct loop from boiler to tank and back.

Gordy

Soooo how comfortable is your installer with all this

alheim

@Gordy Heh well, we'll find out, won't we?

@Bob Bona @Ironman‌ @Eastman‌ & others: I've updated the piping as you've described. Makes sense to me. The boiler control runs only the domestic charging pump during a domestic call.


[Link to schematic here]

But ... then what is the point of having a Primary/Secondary loop? Seems like an unnecessary 3rd circ. Considering that I'll have a 'smart' (or thermic) bypass valve. So how about the following:


[Link to second schematic here]

2 circs, very simple. Could use a Delta P circ like a Grundfos Alpha for the system circ in case many TRV's start to close to prevent dead-heading the pump - and the ES2 has no minimum flow requirement. Thoughts?

alheim

Wow, I've sure learned a lot due to this thread. All I wanted to know was what you thought about 'oversizing' the rads. Instead, you voiced some very important & interesting concerns about the plan overall. Thank you.

Eastman

If I'm not mistaken, the boiler is not protected from low temps originating from a DHW call in your schematic.

Gordy

alheim said:

@Gordy Heh well, we'll find out, won't we?

@Bob Bona @Ironman‌ @Eastman‌ & others: I've updated the piping as you've described. Makes sense to me. The boiler control runs only the domestic charging pump during a domestic call.


[Link to schematic here]

But ... then what is the point of having a Primary/Secondary loop? Seems like an unnecessary 3rd circ. Considering that I'll have a 'smart' (or thermic) bypass valve. So how about the following:


[Link to second schematic here]

2 circs, very simple. Could use a Delta P circ like a Grundfos Alpha for the system circ in case many TRV's start to close to prevent dead-heading the pump - and the ES2 has no minimum flow requirement. Thoughts?

Primary secondary 1st schematic. As valves close in the secondary flow requirements will change. This is the whole reason for p/s. The indirect circ, the boiler circ, and the secondary circ can all have their own flow rates, and not disrupt flow in each circuit.

Now all you need is,a roll of solder

alheim

You are correct, I could do this myself. Main reasons I'm not is it would take me quite awhile, and I hurt my arm in an accident last year. Tough to do this work myself now. There's a lot to do between installing the boiler, the electrics, the flue, the rads, & all the piping. And making it look pretty.

All in all, the entire heating system (incl. the indirect) from scratch including labor is setting me back ~$10k, and I'm not unhappy with that. (Apologies to the board if that counts as 'discussing pricing'.)

@Gordy‌ you will be disappointed to learn that I am going with Schematic #2, without P/S. The plumber wants a lot more to do P/S and I'd need another circ & relays etc. I am including a thermometer at the boiler return and we'll see how she runs. I can always change the piping later.

alheim

What should I set my boiler on top of to raise it off of the floor?

Eastman

@Hatterasguy What is the "low limit on the boiler" you spoke of?

Eastman

@alheim Can I talk you into abandoning the manifold for a nice uncluttered reverse return distribution system?

alheim

Maybe. Assuming you mean piping similar to this, but with radiators instead of the boilers:

[Can't link image.]

First in, last out. Makes sense. I suppose it's slightly simpler. And, I wouldn't have to run as much tube across the basement ceiling. Any other advantages? But ... well, it's late. More tomorrow.

Gordy

I gotta ask does your installer have a piping plan of his own??

alheim

Probably not - just in his head. It's two NYC Local 1 Union guys who do this on the side. They do great work, but as you can tell, probably don't have the technical knowledge of a true hydronic designer. I know, I know. It might be better for me this way though. I'm learning a lot and really enjoying it (less the tight deadline).

I got a copy of John Siegenthaler's "Modern Hydronic Heating" yesterday. Was up til 4am reading. Fascinating stuff. I learned a few things. I think the home run does have a couple advantages over a Reverse-Return. And as per John, I think a Delta P pump is nearly a necessity, esp. w/ the TRV's, unless we used a Differential Pressure Bypass Valve between the supply & return headers (Chapter 11).

And lastly, I'm not totally sold that P/S would offer any big advantage for this simple system - but I'm still trying to work through it.

Like you guys would have done from the start, I need to design the system by looking at flow / losses / requirements. My plumber(s) didn't do any of that.

Gordy

P/s, differential bypass is old school with modern ecm delta p, and delta t circs. look at the taco bumble bee also. It offers delta t mode whic can act as a delta p by holding a set delta t.

Bob Bona_4

Sticking my 2 cents in again. Since you are carefully planning this and if were me, I would mount all the stuff on a board on a wall, and have your primary connections accessible for future boilers. The piping can remain undisturbed--only supply and return on the P/S would be cut.

Really is too bad you aren't springing for the mod con. Home run system, Delta P or T ECM circ, outdoor reset...simple, efficient.

Might you be there already with your venting/low water temp protection etc complications?

Eastman

Critique of overall plan:

You're not taking full advantage of the TRVs.
a) Manifolds and TRVs are somewhat redundant, since balancing is typically a common feature.
b) TRVs are variable flow, variable deltaT. While zoning and balancing is an obvious advantage, they are also exceptional at providing btus with low average seasonal flow rates and relatively fixed supply temps. In a nutshell they are great at providing real time btu heat loss compensation on a room by room basis despite distribution and control challenges.
c) That last advantage, real time btu loss compensation, can only function at a 100% if a source of energy is available to continuously draw off of.
d) The low flow capabilities of TRVs are great for retrofits, as this favors the use of smaller tubing. But again, this capability is diminished if flows must be optimized for fixed boiler output into the distribution system.

Gordy

This thread may be useful when you get your outdoor reset, and how to control it.

Also agree with Bob's comments.

http://forum.heatinghelp.com/discussion/comment/1351613#Comment_1351613

alheim

Gentlemen, here are a few 'before' photos.

I removed mostly all of the existing iron heating pipe, except where it goes up through the walls in a few spots.

We (Dad & I) plumbed the interim domestic water & elec water heater in a morning, with 3/4" & 1/2" PEX, simple, cheap, durable. ProPEX with the Uponor/Milwaukee expansion tool.

The NYC water meter has a line to a battery-powered cellular radio box mounted outside the house, which automatically transits the meter reading to the DEP. The tech said the battery is good for about 5 years, then they'll replace the whole box.

The wiring is by the PO. He tied a new breaker box into the existing cloth BX wire. That will eventually be replaced, along with the ancient outlets & switches. It's messy but in good condition.

Note the hole for boiler venting into the chimney.

I'm writing this from the comfort of a space heater in my bedroom. Boiler install starts Saturday. Thanks for reading.

alheim

Posting photos on this board is finicky, even when you have the markup correct. Here's a link to the album: http://imgur.com/a/vI2NA